GigaLem, I've got no plans to do anymore tilesets at this time.
If I did do anymore, it would most likely not be any Sonic CD or Sonic 3 Competition zones.
I have considered doing Metallic Madness from Sonic CD but decided not to since Scrap Brain is very similar.
Wacky Workbench is another good zone to use, I don't really take much notice of time periods in CD, they all look the same to me.
Sonic 3 competition mode zones: I can't remember the names of specific ones but I honestly don't think any are worth the time. The carnival one (Balloon Park) maybe but there's one in there that looks a lot like Mystic Cave and another which looks like Sandopolis.
Sure, I'll send the entrance and exits to you for the current tilesets when I can